Lucknow, Dec 1 (IANS): Three people were killed in Agra in Uttar Pradesh due to poisonous gas leak during cleaning of a sewage treatment plant, police said on Tuesday.

The leak took place in the Nagla Boodhi area when workers and labourers were sent inside a tank to clean it on Monday evening.

When worker Karan was lowered into the tank, he was hit by some noxious gas with bad odour and lost consciousness. After this another worker, Sonu. and supervisor Ankit got inside the tank to bring Karan back. But they too lost consciousness and fell in the tank.

Police were called but did not possess adequate equipment to carry out the rescue operation.

Later, officials from the fire department were called to assist in the rescue operation and pulled out the three with great difficulty.

They were rushed to a hospital where all the three were pronounced brought dead.

Angry locals and relatives of the dead vandalised the plant office and pelted stones at officials.